It is required in many pipe lining operations to provide in an apparatus for lining pipe with cementitious material a means for adjusting the periphery of the apparatus so that the same may be readily adjusted for use in pipes of various diameters.
Prior endeavors have been directed to effecting circumference change only in a protion of the apparatus, such as by expanding flexible tail sections such as disclosed in U.S. Pat. No. 2,555,377.
Toggle-like expansion joints were used to spread overlapping edges of a section cylinder body such as is illustrated in U.S. Pat. No. 126,100.
A neck made of flexible material such as rubber, was employed to permit the flexing of the side wall section of a cylinder body in U.S. Pat. No. 2,711,000.
By restricting and limiting the expansion or flexibility of only a portion of the bell body, as evidenced by the prior art, the prior art devices created unsupported localized stress, that by reason of the wet weight of the cementitious material, soon ruptured, bent or broke all or parts of the expanding parts of those devices, rendering a void in the placement and packing of the lining material against the pipe to be lined.
It is an object of this invention to eliminate the problems and structural defects of the prior art.